import java.util.Scanner;
//只打印一次
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        while(scanner.hasNext()){
            String str = scanner.nextLine();
            System.out.println(func(str));
        }
    }
    public static String func(String str){
        boolean []bool = new boolean[127];
        StringBuilder string = new StringBuilder();
        for (int i = 0; i < str.length(); i++) {
            char ch = str.charAt(i);
            if(!bool[ch]){
                string.append(ch);
                bool[ch] = true;
            }
        }
        return string.toString();
    }
    public void merge(int[] nums1, int m, int[] nums2, int n){
        int i = m - 1;
        int j = n -1;
        int k = m + n -1;
        while(i >= 0 && j >= 0){
            if(nums1[i] > nums2[j]){
                nums1[k--] = nums1[i--];
            }
            else{
                nums1[k--] = nums2[j--];
            }
        }
        while(i >= 0){
            nums1[k--] = nums1[i--];
        }
        while(j >= 0){
            nums1[k--] = nums2[j--];
        }
    }
}
